Implement `Args` to pass arguments to scripts.
Rename Args to ScriptArgs for clarity.
Unit tests for `--` parsing on command line.
Additional unit tests.
Merge pull request #228 from sblom/script-args

Implement `Args` to pass arguments to scripts.
Merge branch 'dev' of https://github.com/scriptcs/scriptcs into repl-refactor

Conflicts:
	src/ScriptCs.Core/IScriptExecutor.cs
	src/ScriptCs.Core/ScriptExecutor.cs
	src/ScriptCs/Command/ExecuteScriptCommand.cs
	test/ScriptCs.Core.Tests/ScriptExecutorTests.cs
	test/ScriptCs.Tests/ExecuteScriptCommandTests.cs